CVE-2026-32756 in admidio
Summary
by MITRE • 03/20/2026
Admidio is an open-source user management solution. Versions 5.0.6 and below contain a critical unrestricted file upload vulnerability in the Documents & Files module. Due to a design flaw in how CSRF token validation and file extension verification interact within UploadHandlerFile.php, an authenticated user with upload permissions can bypass file extension restrictions by intentionally submitting an invalid CSRF token. This allows the upload of arbitrary file types, including PHP scripts, which may lead to Remote Code Execution on the server, resulting in full server compromise, data exfiltration, and lateral movement. This issue has been fixed in version 5.0.7.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/23/2026
The vulnerability identified as CVE-2026-32756 affects Admidio version 5.0.6 and earlier, representing a critical unrestricted file upload flaw within the Documents & Files module. This issue stems from a fundamental design weakness in the UploadHandlerFile.php component where the interaction between Cross-Site Request Forgery token validation and file extension verification creates an exploitable condition. The flaw specifically manifests when an authenticated user with appropriate upload permissions attempts to bypass the system's file type restrictions through deliberate manipulation of CSRF token validation.
The technical implementation of this vulnerability exploits the flawed validation logic that fails to properly enforce file extension checks when an invalid CSRF token is submitted. This design flaw allows an attacker to upload malicious files with extensions that would normally be rejected by the system, including dangerous formats such as php, aspx, or other server-side script types. The vulnerability demonstrates characteristics consistent with CWE-434 Unrestricted Upload of File with Dangerous Type, which specifically addresses the risk of allowing file uploads without proper validation of file content or type. The interaction between CSRF protection mechanisms and file validation creates an unexpected bypass condition that undermines the security controls designed to prevent malicious file uploads.
Operationally, this vulnerability presents a severe risk to system integrity and security posture, as it enables remote code execution capabilities through the upload of malicious scripts. When successful, the vulnerability allows attackers to execute arbitrary code on the server, potentially leading to complete system compromise. The attack chain typically begins with authentication, followed by exploitation of the CSRF token bypass mechanism, and concludes with the execution of malicious payloads that can facilitate data exfiltration, privilege escalation, and lateral movement throughout the network. This vulnerability directly maps to ATT&CK technique T1190 Exploit Public-Facing Application, where adversaries leverage weaknesses in web applications to gain unauthorized access and execute malicious code.
The remediation for CVE-2026-32756 requires immediate deployment of version 5.0.7 or later, which addresses the core validation logic flaw in UploadHandlerFile.php. Organizations should implement comprehensive patch management procedures to ensure all affected systems receive the update promptly. Additional mitigation strategies include implementing more robust file validation mechanisms that do not rely on CSRF token status for extension verification, deploying web application firewalls to detect and block suspicious upload patterns, and conducting regular security assessments of file upload functionalities. The vulnerability highlights the importance of proper input validation and the need for security controls that remain effective regardless of authentication state or token validity, as demonstrated by the failure of CSRF protection mechanisms to maintain their intended security boundaries when interacting with file validation logic.